复合冲击破岩钻井新技术提速机理研究

为了解决PDC钻头钻遇硬地层时出现的机械钻速低、钻头粘滑振动失效快等问题，提出了PDC钻头复合冲击钻井破岩新技术，并对该技术的提速机理进行了研究。根据建立的PDC钻头受单向轴向冲击及复合冲击时的扭转振动模型，对PDC钻头的运动规律进行了分析，并利用ABAQUS软件对岩石受单向轴向冲击及复合冲击时所受的剪切力进行了模拟。模拟结果表明，PDC钻头受单向轴向冲击时切削齿的切削深度会增加，但是会造成PDC钻头扭转振动；复合冲击大大提高了PDC钻头对岩石的剪切作用，降低了岩石的阻抗扭矩，从而抑制了PDC钻头受单向轴向冲击所产生的扭转振动。研究表明，PDC钻头复合冲击钻井破岩新技术能够增加切削齿的切削深度并抑制扭转振动，提高硬地层的机械钻速。 

The Rock Breaking Mechanism of the Compound Percussive-Rotary Drilling Method with a PDC Bit

To provide satisfactory solutions to the low rate of penetration (ROP) and pre-mature failure of the PDC bits caused by stick-slip vibration while drilling through hard formations, an innovative compound percussive-rotary drilling technique with a PDC bit was proposed in this paper and the rock-breaking mechanisms of the technique were reviewed. By using the torsion models for one-way axial percussions and compound percussion of PDC bits, patterns of movements of such PDC bits were analyzed. In addition, ABAQUS was used to simulate shearing forces on rocks during one-way axial percussion and compound percussion. Research results showed that PDC bits under one-way axial percussion may have significantly enhanced the cutting depths of the teeth. At the same time, PDC bits may experience torsional vibration during the process, and compound percussion could significantly enhance shearing performances of PDC bits on formation rocks by reducing resistance torques. In this way, torsional vibration of PDC bits induced by one-way axial percussions could be reduced dramatically. In conclusion, compound percussion drilling techniques with PDC bits can effectively enhance ROP in drilling through hard formations by enhancing cutting depths and reducing torsional vibration.